SEOUL—Rising investor demand for corporate payouts and a coming slate of new dividend funds in South Korea is putting pressure on the country’s biggest companies to return more cash to shareholders, South Korea’s stock market chief said.

Choi Kyoung-soo, the chairman and CEO of Korea Exchange, or KRX, expressed optimism in an interview with The Wall Street Journal that the mood was changing in a country that has earned a reputation for being stingy with its corporate cash.